Much like the Alan Moore/Dave Gibbons comic book miniseries “Watchmen,” Orson Scott Card’s sci-fi military novel “Ender’s Game” was deemed unfilmable by the author for years. But just as Zack Snyder found a way to bring “Watchmen” to the big screen, so too has Gavin Hood with “Ender’s Game.” Despite having never read the novel myself, it’s easy to see why Hollywood had so much trouble adapting the source material, because although Hood has succeeded in some respects, it feels like a more streamlined version that’s missing a lot of the complexity that made the novel so revered in the first place. It’s like “Harry Potter” meets “Full Metal Jacket,” and while that’s certainly an intriguing mash-up, the movie doesn’t quite live up to the book’s reputation.

Following an attack on Earth by an alien species known as the Formics – in which millions of people were killed before a brave fighter pilot single-handedly defeated the enemy fleet – the planet’s military leaders have begun planning for their return. At the forefront of the defense effort is Colonel Graff (Harrison Ford), who runs a program training gifted youngsters with the best tactical minds in the hope that they can lead Earth to victory should the insect-like Formics return again. One of the program’s newest recruits is 12-year-old outsider Andrew “Ender” Wiggin (Asa Butterfield), a brilliant strategist whom Graff believes has the potential to save their entire species. Sent to an orbiting space station for a boot camp called Battle School to train with the other top recruits in a series of physical and mental challenges, Ender is pushed to his limits by Graff to prepare him in time for the next attack.

It’s been a couple years since Butterfield’s last role in Martin Scorsese’s “Hugo,” but he delivers yet another strong performance as the precocious title character. Scrawny and seemingly unimposing, there’s a coldness to the way Butterfield portrays Ender that suggests there’s a darker side to him, and that only makes him a more fascinating protagonist. Ford also turns in some solid work as the overbearing Graff, but the rest of the cast is pretty forgettable, especially the other kids in the program, who aren’t given very much personality with the exception of Moises Arias’ borderline psychotic (and hilariously named) Bonzo Madrid. There are three Oscar nominees/winners in the cast – Hailee Steinfeld, Ben Kingsley and Viola Davis – and yet they’re all so underutilized that it’s a wonder they even bothered showing up.

Though one could argue that the basic concept of “Ender’s Game” is a little foolish, it’s still a pretty interesting piece of science fiction that raises some big questions about violence, war and genocide, not to mention the manipulation of children into becoming soldiers through games. Unfortunately, while the novel’s social commentary hasn’t been completely lost in translation from page to screen, it’s a lot more muted as a result of Hood’s restructured narrative. The story is lacking the necessary depth to give it that epic scope, and it feels rushed at times, particularly in regards to Ender’s rapid progression through the ranks. What Hood does get right, however, is the look of the film, including a zero-gravity laser tag game that puts Quidditch to shame. It’s during these sequences that the film really shines, but they’re not enough to raise “Ender’s Game” above mediocrity. That’s not to say the movie isn’t entertaining, but for a novel that’s so highly regarded by sci-fi fans, it should have been a lot better.